What is epigenetics? Does this new field hold promise for understanding the causes of ASD?

“Got Questions?” is a new weekly feature on our blog to address the desire for scientific understanding in our community. We received over 3000 responses when we asked what science questions were on your mind. We answered a few here and the Autism Speaks Science staff will address the other themes we received in this weekly post.

Scientists have long wondered how experiences during a person’s lifetime can alter behavior and body functioning. In the early 1800’s Jean Batiste Lamarck suggested that giraffes’ necks grew long through many generations of stretching to reach distant leaves. That theory eventually fell to evolution–pressures from the environment selectively amplify or quiet certain traits that are variably present within a population. Later, the DNA code was found to be the mechanism for inheritance and the level at which selective pressure acts.

Today’s scientists see hints of Lamark as they peer into the molecular biology of inheritance.

Consider DNA to be a library of books that encode genes. These “genetic books” must be read so that proteins can be formed from the code. Some genetic books are open and available for reading by the cell’s molecular machinery. Others maybe temporarily unavailable and still others are in the restricted section—essentially permanently unreadable.

Experiences throughout an individual’s life create tags on the genetic code, marking it as available or not for reading. The molecular methods that control the availability of the genetic code are collectively referred to as epigenetic mechanisms. Literally meaning “above the genome”, epigenetic mechanisms tag DNA with different chemical marks, such as methyl or acetyl groups. Certain tags can increase the reading frequency, resulting in more protein building-blocks transcribed from the DNA code, and more of that gene “expressed”. Other tags result in a particular piece of the genetic code to be skipped during reading.

A host of environmental agents and interactions may leave epigenetic marks on the genome. Early life stress, smoking, exposure to toxins may all leave epigenetic marks either creating or removing barriers for protein creation.

Here is where Lamark comes in. Most epigenetic marks are removed before the sperm and egg meet to form an embryo, but sometimes, epigenetic marks remain. This is one mechanism by which environmental exposures can be passed along from parent to child.

The study of epigenetics and gene expression in autism is underway and early findings are exciting. Some of the genetic syndromes associated with autism, such as Angelman and Prader-Willi syndrome, result from epigenetic marks that render one parent’s genetic contributions unreadable. Recently, gene expression studies from the blood and even brain tissue of individuals with autism have shown differences in the activity of patterns of genes that are involved in brain development and function.

This is an exciting area of research and we look forward to sharing more details as we learn more from the science.

Yes, we watched a study on this about 6 months ago and definitely feel it will hold some answers (but not all). Autism is tricky and I still feel that there are at least 4 different ways to have it. Genetics, Immune/viral/vaccines, allergic reaction to environmental toxins (pesticides/air pollution that causes inflammation, chemical or drug exposure (both ingested and inhaled) causing harm to the fetus. There are at least 4 avenues. This one is linked to the genetic part (possibly 25%).

The one area not considered in the four ways of getting autism, nutrition/diet is not considered. My research has shown this to be the basic cause for autism and the other four are secondary at best. The sixty or more nutrients that have been found to be deficient in those with autism appears to hold the answer for cause, prevention, and cure.

No offense intended to these families but I son’t see how Angelman or Prader -Will has anything to do with the vast majority of ASD cases which are idiopathic in nature. Angelman and Prader are entirely genetic diseases, they cannot be acquired after an environmental insult.

Can’t we just study one some of ASD’s barely researched environmental triggers and the document the effect these substances have on the infant brain? We don’t need to get into the genome right now. It is prohibitively expensive research – we have so much higher priority here and now environmental research to do.

1)Let’s start by studying the viral interaction of all 42 vaccines given to babies under 2
2)Then let’s study the impact of the most commonly used pesticides on American lawns
3)Then lets study some ASD clusters- like Brick Township and the Somalis in Minneapolis. Autism averages 1 in 50 kids in these communities! Rather than focusing on Angelman’s Syndrome why not study the environmental factors behind these ASD clusters now?

‘No offense intended to these families but I son’t see how Angelman or Prader -Will has anything to do with the vast majority of ASD cases which are idiopathic in nature. Angelman and Prader are entirely genetic diseases, they cannot be acquired after an environmental insult’.

Actually the majority of cases of Angelmans Syndrome and Prader-Willi Syndrome are the consequence of a de novo mutation meaning that the genetic mutation is not present in either parent. Other genetic Syndromes associated with autism some of which are over 99% caused by a de novo mutation not present in either parent, such as Rhetts Syndrome and Downs Syndrome. In Timothy Syndrome over 90% of the cases are de novo mutations not present in either parent. Velo-Cardio-Facial syndrome is also the consequence of a de novo mutation in over 90% of the cases. Tuberous Sclerosis is one of the most studied genetic syndromes associated with autism. Two thirds of Tuberous Sclerosis cases are also the consequence of a de novo mutation not present in either parent. The majority of Williams Syndrome cases are also de novo mutations not present in either parent.

One of the misleading claims is that autism must be genetic since it is associated with these genetic disorders. The problem is that these genetic conditions for the most part are NOT heritable at all since the mutations are not present in either parent. There is Little research into the causes of de novo genetic mutations, however, evolutionary theory implicates environmental factors in the cause of these de novo genetic mutations.

Another problem is the misdiagnosis of the syndromes as being on the ‘autism spectrum’. Like Rhetts Syndrome, Angelmans Syndrome has such a profound effect in all sorts of ways that the association with autism is quite questionable.

If you visit the website of the Angelman’s Syndrome Foundation they state on their website that Angelmans Syndrome is often misdiagnosed as cerebral palsy or autism:

So, Katie, you are absolutly right when you state that Angelmans Syndrome and Prader-Willis Syndrome may not have anything at all to either with idiopathic autism, and additionally these syndromes may not have a place anywhere on the ‘autism spectrum’.

LOL. If Autism Speaks actually researched vaccines they would easily have already done the Vaccinated vs. Unvaccinated study that would end the argument once and for all. We would know what proportion of the autism epidemic is due to vaccines, and what is due to other environmental insults. If Autism Speaks won’t fund this study, somebody else will. And at that point the “Science”, what Pat Kemp states is the true “Autism Speaks Brand”, will be reduced to nothing more than a bunch of over paid pharma and insurance industry sympathizers who betrayed an entire community.

I called in to the Diane Rehm show the day that an author was discussing her book on fetal origins and asked a question about epigenetics and the expression of genes associated with autism and was fobbed off with a ‘Jennifer, you did not cause your daughter’s autism’ reply rather than really discussing it. I’m so glad that this is being looked into further. Both my pregnancies were plagued with hyper-emesis and stress and very traumatic for both me and the babies, including off-label uses of zophran and phenagren to try to control the vomiting, and while I don’t think any of that caused the autism, could it have affected gene expression in the way diabetes and heart disease seem to be affected by pre-natal trauma?

I’m new to this so if I ask a question that has already been asked I apologize. I wonder if there are good articles about teenagers with Autism. My son turned 15 at the end of October and for the last couple of years he’s had some major issues with anger. He has hormones to deal with as well as adjusting to high school and…oh yeah, his medications too. They make him sleepy and his teacher’s aid who goes to all of his morning classes with him was only trying to help him by shaking him awake received the full effects of my son’s anger and he received an office referral for his disrespectful and embarrassing and LOUD comments to her. Being a teenager is a toxic stew anyway but,as you may know, all of these things being added to the stew-pot to create the perfect storm.